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Microbial transformations of nitrification and denitrification are the main sources of nitrous oxide (N2O) from soils. Relative contributions of both processes to N2O emissions were estimated on an agricultural soil using 15N isotope tracers (15NH4+ or 15NO3-), for a 10-day batch experiment. Under unsaturated and saturated conditions, both processes were(More)
Constitutive heterochromatin comprising the centromeric and telomeric parts of chromosomes includes DNA marked by high levels of methylation associated with histones modified by repressive marks. These epigenetic modifications silence transcription and ensure stable inheritance of this inert state. Although environmental cues can alter epigenetic marks and(More)
The relationship between capillary density and mitochondrial volume density in skeletal muscle tissue is investigated on 25 African mammals ranging in body mass from 0.4 to 251 kg. As a general trend higher capillary densities, NA (c,f) are found in muscles with higher volume densities of mitochondria, Vv(mt,f). The individual data however show considerable(More)
The turnover of organic matter in soil depends on the activity of microbial decomposers. However, little is known about how modifications of the diversity of soil microbial communities induced by fresh organic matter (FOM) inputs can regulate carbon cycling. Here, we investigated the decomposition of two 13C labeled crop residues (wheat and alfalfa) and the(More)
It is widely assumed that agricultural practices have a major impact on soil living organisms. However, the impact of agricultural practices on soil microbes is poorly known, notably for species richness, evenness, and taxonomic composition. The taxonomic diversity and composition of soil indigenous microbial community can be assessed now using(More)
To investigate changes in the ultrastructure of the different muscle fiber types induced by endurance training ten sedentary subjects (five women and five men) were exercised on bicycle ergometers 5 times a week for 30 min. After 6 weeks of training there were significant changes in VO2max (+14%), in the percentage of type I (+12%) and type IIB fibers(More)
Maintenance of CG methylation ((m)CG) patterns is essential for chromatin-mediated epigenetic regulation of transcription in plants and mammals. However, functional links between (m)CG and other epigenetic mechanisms in vivo remain obscure. Using successive generations of an Arabidopsis thaliana mutant deficient in maintaining (m)CG, we find that (m)CG loss(More)
Double-stranded RNAs (dsRNAs) and their 'diced' small RNA products can guide key developmental and defense mechanisms in eukaryotes. Some RNA-directed mechanisms act at a post-transcriptional level to degrade target messenger RNAs. However, dsRNA-derived species can also direct changes in the chromatin structure of DNA regions with which they share sequence(More)
The variability of structures supporting tissue oxygen transport (capillaries) and oxygen consumption (mitochondria) was analyzed in skeletal muscles of wildebeest and dik-dik. Regional differences in mitochondria and capillary densities within individual muscles were found for M. semitendinosus (twofold) but not for M. longissimus dorsi and diaphragm.(More)
An evaluation is made of the relative efficiency (precision of the final estimate per unit time of measurement on a given set of sections) of different methods for planar analysis aimed at estimating aggregate, overall stereological parameters (such as VV, SV). The methods tested are point-counting with different densities of test points (4 less than or(More)